What is the best finishing process to choose for a keychain?

Q. Hello,

I am planning on manufacturing a keychain or a carabiner and I am trying to find which is the best finishing process for this kind of objects if I want to achieve a matte black color.

The things that I am looking for in a finishing process are:

1. Endurance. Since it's an object that will be in a pocket with key and coins, I don't want the color to chip with use.

2. Achieve a matte black color (not a very dark grey and not glossy.)

3. The finishing process must be able to be applied on either steel or zinc alloy material. I understand that I can also zinc-plate a steel surface, but that would create additional costs.

From my brief research, I see that I have two choices; either powder-coating or electroplating. My questions are the following:

1. Are those two the only good finishing processes for what I want to do or is there something else I am missing?

2. Can I achieve a true black with electroplating?

3. Is the only way to electroplate steel an underplate of zinc?

4. Will powder coating sustain the everyday use of a keychain/carabiner or the paint will gradually chip?

Any other thoughts that might arise from my questions and I didn't think of to write here would be greatly appreciated.

Thank you all in advance,
Panos

Q. I am planning on producing a carabiner keychain (not to be used . The material I'll use will be either aluminum, stainless steel or titanium.

I would like to know what is the best finishing process for each of the above materials when what I want to achieve is the following:

1. A real BLACK and not some very dark grey color.
2. A finish that doesn't chip or rub off (since it will be inside a pocket with keys and coins).
3. A finish that is matte and not glossy.

So, keeping in mind the above, what would be the best process for each material?

Best,
Panos